The present invention relates to an automatic and manual linear reversion control mechanism for a hydraulic servo actuator and more particularly to a device for transferring control linearly between the automatic (fly by wire) control and the manual control.
Hydraulic control mechanisms typically include a main control valve for controlling the flow of fluid from a source to an actuator through either one of two ports and from the actuator to the source through a return conduit. The actuator position is fed back through an actuator feed back linkage to the main control valve to provide the desired control information.
In hydraulic control systems used for aircraft and other vehicle navigation, a manual control mechanism and an automatic control mechanism are typically provided to control the position of the control valve. Thus the position of the main control valve is controlled by the automatic control and the manual control as well as by the actuator feed back to thereby control the flow of fluid through the control valve and ultimately the position of the load connected to the actuator.
Various prior art devices have sought to transfer control between the automatic control and the manual control in a smooth manner. However, such devices include complicated linkage and joint arrangements and have a dead band of operation during the transfer between the manual and automatic controls. The backlash and friction in the transfer between the automatic and manual controls in such devices therefore renders the transfer between manual and automatic command rather awkward. The best prior art known to applicant is illustrated in U.S. Pat. Nos. 1,199,036; 1,119,324; 3,093,121 and 3,726,186.